Nervous system disorders affect millions of people, causing a degradation of life, and in some cases, death. Nervous system disorders may include disorders of the central nervous system and peripheral nervous system. Some nervous system disorders may be considered “neurological movement disorders,” and may include, for example without limitation, epilepsy, Parkinson's disease, essential tremor, dystonia, and multiple sclerosis (MS). Additionally, neurological movement disorders may include mental health disorders and psychiatric disorders which also affect millions of individuals and include, but are not limited to, anxiety (such as general anxiety disorder, panic disorder, phobias, post traumatic stress disorder (PTSD), and obsessive compulsive disorder (OCD)), mood disorders (such as major depression, bipolar depression, and dysthymic disorder), sleep disorders (e.g., narcolepsy), obesity, anorexia, and chronic pain disorders. Neurological movement disorders may be characterized by periods of involuntary movements and/or loss of muscle control.
As an example of a neurological movement disorder, Parkinson's Disease (PD) is generally characterized by poverty and slowness of movement (akinesia and bradykinesia), muscle stiffness (rigidity), tremor at rest, and gait and balance abnormalities that may lead to an inability to perform normal daily life activities. Some patients suffering from neurological movement disorders may also develop symptoms called dyskinesias and motor fluctuations, which may be a side effect of certain anti-Parkinson's medication. It is believed that PD is caused by the degeneration of dopaminergic neurons in the substantia nigra pars compacta, a brain structure of the basal ganglia involved in the control of movement. The loss of dopamine in the basal ganglia is believed to secondarily cause a cascade of abnormal activity in the other nuclei of the basal ganglia, thalamus and cortex. This has been detected in animals and humans as changes in neuronal firing patterns, firing frequencies, and in the tendency of these neurons to fire in an oscillatory manner. These abnormal oscillations and firing patterns are thought to underlie the classic motor symptoms of PD and have been shown to be reversible with the dopamine medication used to effectively treat PD.
There are various approaches in treating nervous system disorders, such as neurological movement disorders. Treatment therapies can include any number of possible modalities alone or in combination including, for example, electrical stimulation, magnetic stimulation, drug infusion, and/or brain temperature control. Each of these treatment modalities may be employed using closed-loop feedback control. Such closed-loop feedback control techniques may receive neurological signals (e.g., from a monitoring element) carrying information about a symptom or a condition of a nervous system disorder. Such a neurological signal can include, for example, electrical signals (such as local field potentials (LFPs), electroencephalogram (EEG), electrocorticogram (ECoG), and/or electrocardiogram (EKG) signals), chemical signals, and/or other types of biological signals (such as changes in the quantity of neurotransmitters).
For example, U.S. Pat. No. 5,995,868 to Dorfmeister et al., incorporated herein by reference in relevant part, discloses a system for the prediction, rapid detection, warning, prevention, or control of changes in activity states in the brain of a patient. Use of such a closed-loop feed back system for treatment of a nervous system disorder may provide significant advantages.